CAPE CANAVERAL, Florida (Reuters) - A flagship U.S. space observatory designed as a powerful successor to the Hubble Space Telescope needs another $1.5 billion to make a launch date in 2015, an oversight panel reported on Wednesday.
"I doubt that we're going to find $250 million," Scolese said on a conference call with reporters.
In a best-case scenario, the review panel pegged the telescope's overall cost at $6.5 billion, up from a $5 billion estimate two years ago. That cost will grow even more if the launch date slips beyond September 2015.
The report, ordered by Senator Barbara Mikulski, a Maryland Democrat, determined that NASA's cost estimates to develop the technologies and build the observatory were faulty from the beginning.
Scolese said the U.S. space agency had brought in new management to oversee the telescope's development and clamp down on costs.
"We aren't in the business of cost overruns. We're not pleased we had a cost overrun. This is something we have to fix," Scolese said.
The review panel determined the telescope, a potential boon for astronomy, was in good shape technically.
"The James Webb (telescope) is a hugely more powerful facility than Hubble, 100 times more at least. The science just underpins so much of what we're looking to do in the future," he said.
Hubble, carried into orbit outside the distortion of Earth's atmosphere by a space shuttle in 1990, has been a vital research tool and led to breakthroughs in astrophysics including imaging the first galaxies.
In a statement, NASA administrator Charles Bolden said, "I am disappointed we have not maintained the level of cost control we strive to achieve -- something the American taxpayer deserves in all of our projects."